No, you do not need to trade to fill up the Sinnoh Dex if you're just looking for ones that are recorded as being "seen" in Platinum because all 210 Pokémon in the Sinnoh Dex can be recorded as being "seen" in Platinum however you do need to trade if you want to fill up your National Dex cause some Pokémon like Stunky or Glameow are only available in Diamond and Pearl. You must trade them to Platinum to record them as "obtained" in your National PokéDex.
Quick question. Can you not speak english? What he is trying to say is you just have to battle everyone, and look for a few. They scammed us when they did that, because I don't like to lose, it makes me angry.
no, you need to see/catch Rotom to complete the dex.
to do that, you have to go to the Old Cheteau at night, and thump the tv and rotom will appear
You don't have to catch them all, you only have to see them all.
You catch Garatina, Dialga,Palkiia,and all the lake Pokemon but mainly Garatina
You can't get Thunderus in Pokemon Platinum at all. By then when Pokemon Platinum was made, no one knew that Pokemon Black and White were going to be made.
Cheat, trade, migrate, catch
Just catch them,you dummy!
I dont know what happen in diamond, but in platinum you can catch ! and ? unowns.
You have to see all Pokemon Pokemon. But not the ones on nationaldex.
find all 210 Pokemon on sinnoh pokedex then visit profeser rowan
you don't need to catch them just see all the Pokemon in the hoenn pokedex
You can catch Sinnoh Pokemon in Pokemon platinum, but you need to migrate and trade unless you have an action replay
You catch them.
yes the sister of dawn in sandgem city but she will tell you one Pokemon a day
To finish the sinnoh dex (Pokemon platinum's,diamond, and pearl dex) you just need to see every Pokemon not catch every Pokemon.
You can catch and find all the sinnoh Pokemon and when you see all the sinnoh Pokemon you get the national dex and find and catch all the pokeradar Pokemon.You get the pokeradar when you get the national dex.
You catch Garatina, Dialga,Palkiia,and all the lake Pokemon but mainly Garatina
You get the diploma from catching all Pokemon from Nationaldex and Hoenndex.
You can't get Thunderus in Pokemon Platinum at all. By then when Pokemon Platinum was made, no one knew that Pokemon Black and White were going to be made.
depending on where you go and what you do you can catch all of them, every Pokemon in existence